The present invention relates to a satellite locator system used with a mobile unit, such as a recreational vehicle, bus, automobile, over the road commercial freight truck, train or ship for searching the sky for a selected satellite and locking onto the satellite.
The conventional satellite communications systems have microwave receiving antennas or parabolic reflector dishes connected to arms supporting feedhorns and signal converters. Cables couple the convertors to receivers which provide converted output signals for conventional televisions. The antennas are mounted on supports fixed to the ground or a building. Antenna direction adjusters associated with the supports and antennas are used to locate the antennas in the direction of a selected satellite. The adjusters change the elevation and azimuth angles of the antennas and maintain adjusted positions of the antennas. The antenna adjustments depend on the location of the antennas on the surface of the Earth since the satellites are in orbit in the Clarke Belt and remain in fixed positions relative to the surface of the Earth. When the satellite communication systems are moved to a new location the elevation and azimuth angles of the antennas must be adjusted to align the antennas with the selected satellite. Mobile units, such as motor homes, travel and recreational vehicles have been equipped with satellite communication systems for conventional televisions. These communication systems have satellite signal receiving antennas mounted on the roofs of the vehicles. The antennas include parabolic dishes which are exposed to the outside environment, wind, insects, mud, dirt, dust, snow, ice and UV radiation. In some installations, the exposed dishes are pivoted to a generally horizontal non-functional position when the vehicle is moving to reduce the wind forces on the dishes. The dishes must be returned to their operating positions and the elevation and azimuth locations of the dishes must be adjusted to locate a desired satellite. The dishes are operatively associated with gear trains manually operated with knobs and cranks to change the elevations and azimuth positions of the dishes to search for a selected satellite. Tripod and hand crank mounts for portable satellite dishes are disclosed by Y. Nonaka in U.S. Pat. No. 5,019,833. A linear actuator operable to pivot a satellite dish is disclosed by C. R. Schudel in U.S. Pat. No. 4,804,972. In some satellite communication systems positioners having electric motors are used to operate the gear trains. The dishes are attached to polarmounts which enables the dishes to track the whole of the Clarke Belt. M. Vematsu, T. Ojima and M. Ochiai in U.S. Pat. No. 5,309,162 disclose a satellite antenna for a mobile body having electric motors to elevate and rotate the antenna. The automatic satellite locator systems have antennas that are exposed to the outside environment.
The satellite locator system is used with mobile units, such as recreational vehicles, ships, trains, or buses, to locate a selected satellite when the mobile units are stationary in different locations. The system scans the sky to locate one or more satellites orbiting in the Clarke Belt. When the desired satellite is located, the scanning ceases and the antenna or dish is locked onto the satellite. A dome of dielectric material mounted on the mobile unit, such as the roof of a recreational vehicle, covers the dish, feedhorn, converter, and dish mount and elevation and azimuth controls to provide protection from wind, rain, snow, ice, dust, dirt, insects and other environmental conditions. The dome is a lightweight ultra violet light protected plastic semi-hemispherical cover having an inside concave surface located in close proximity to the converter to improve satellite signal strength. The dome covers a vacuum formed or injection molded plastic concave paraboloid or antenna reflector dish that is vacuum metalized or coated with aluminum for optimal reflectivity. The dish has a plastic parabolic body with a completely metalized surface, which has virtually, zero ohm resistance across the antenna surface. Dish elevation and azimuth rotation is achieved with electric stepper motors. The elevation motor periodically reverses its drive to vary the elevation of the dish simultaneously with the rotation of the dish to establish a band or sawtooth 360xc2x0 search pattern. This search pattern allows for scanning a greater area of the sky in a shorter period of time than conventional satellite systems having linear elevational search patterns or linear azimuth search patterns that are parallel or perpendicular to the Earth""s surface. The motors are controlled with the use of electronic controls including a microprocessor and an electronic level sensor to compensate for vehicle tilt. The electronic controls can be programmed and reprogrammed to upgrade the satellite locating system. Additional components can be added to the controls to provide a satellite locating system to continuously search and lock onto a satellite during movement of the mobile unit. The microprocessor is programmed to monitor and maximize signal strength and converter to receiver polarization to identify a satellite. The control operates to monitor voltage changes of the receiver to determine if the signals from the located satellite matches the receiver and service provider""s operating criteria. When the voltage change stops, a signal is sensed by the console which indicates to the user that the satellite locator apparatus has locked onto a satellite. The satellite signals are continuously averaged during the search for satellites. The average signal level is used as a reference which changes dynamically during the satellite search. When a search for a second satellite is started, the last average signal is used as a starting signal average. In the event that the located satellite is not compatible with the receiver or service provider, the control stores data representing the location of the satellite and bypasses the satellite in a search for another satellite. The 12 volt DC power of the vehicle is used to power the system. The operator or person within the vehicle uses a remote console electrically connected to the electronic control to commence the scanning operation for a desired satellite, monitor the status of the, system, and terminate the scanning when the dish is pointed at the selected satellite. One form of the console has ON/OFF switches, a 12 digit key pad and a 2 digit numeric display that communicates serially with the antenna unit and permits the operator to monitor status and control the elevation and azimuth of the dish. In another form, the console has a single three-position switch and two lights that indicate the system""s status and when a satellite has been located and locked onto the system.